Twisted 10 twisted.python.logfile (deferred).py

    def rotate(self):
        """
        Rotate the file and create a new one.

        If it's not possible to open new logfile, this will fail silently,
        and continue logging to old logfile.
        """
        
        def rotateOldLogs():
            """
            Rotate log files that aren't the current, and remove any
            that exceed maxRotatedFiles.
            """
            if self.rotationInProgress:
                return False
            self.rotationInProgress = True
            
            if not (os.access(self.directory, os.W_OK) and os.access(self.path, os.W_OK)):
                self.rotationInProgress = False
                return False
            logs = self.listLogs()
            logs.reverse()
            for i in logs:
                if self.maxRotatedFiles is not None and i >= self.maxRotatedFiles:
                        os.remove("%s.%d" % (self.path, i))
                else:
                        os.rename("%s.%d" % (self.path, i), "%s.%d" % (self.path, i + 1))
            return True
        
        def cb_rotateCurrLog(rotate_old_logs_success):
            """
            Rotate the currently open log file
            """
            if not rotate_old_logs_success:
                return
            
            self._file.close()
            os.rename(self.path, "%s.1" % self.path)
            self._openFile()
            
            self.rotationInProgress = False
            
        def eb_rotateFailed(failure):
            """
            Rotation failed. Consume the error.
            """
            self.rotationInProgress = False
            failure.trap(OSError, IOError)
        
        return threads.deferToThread(rotateOldLogs).addCallback(cb_rotateCurrLog
                                                   .addErrback(eb_rotateFailed)